1. Field of the Invention
The present invention relates to a grommet for a wire harness, specifically, a grommet mounted on a wire harness routed in an automobile and mounted in a through-hole of a vehicle body panel, the grommet concurrently enhancing waterproof performance of a seal lip thereof tightly attached to a periphery of the through-hole and reducing force to insert the grommet.
2. Description of Related Art
A grommet for a wire harness of this type is attached to a wire harness inserted through a through-hole of a body panel that partitions inside and outside of a passenger cabin. Then, a seal lip is tightly attached to a periphery of the through-hole to shield the passenger cabin from water.
For example, in a grommet 100 disclosed in FIGS. 9(A) and 9(B) of Japanese Patent Laid-Open Publication No. 2008-218110, which is an earlier application of the inventor of the present invention, a resin inner 102 is combined with a grommet main body 101 composed of a rubber or elastomer; a periphery of a through-hole H in a body panel P is placed between a seal lip 105 provided to the grommet main body 101 and an engagement tab 106 provided to the resin inner 102; and the seal lip 105 is pressed against the periphery for protection from water.
In order to increase waterproof performance of a grommet mounted in a through-hole, a large insertion force is required to insert the grommet into the through-hole, thus increasing a burden on a worker. In particular, with a seal lip that lacks flexibility, the insertion force cannot be reduced during insertion of the grommet. Meanwhile, a readily flexible seal lip can reduce the insertion force; however, the waterproof performance decreases in a case where the seal lip bends and deforms during insertion in a state where the grommet is mounted in the through-hole.
In the grommet shown in FIGS. 9(A) and 9(B) above as well, when the seal lip 105 does not bend, it is difficult to insert the resin inner 102 into the through-hole H in the body panel P. However, when the seal lip 105 bends outward and deforms excessively, the seal lip 105 cannot be directly pressed against the body panel P, and thus reduces sealing performance.